ABB RED615 Technical Manual page 544

Section 5
Protection related functions
538
The operation of an inrush current detection function can be described using a
module diagram. All the modules in the diagram are explained in the next sections.
A070694 V2 EN
Figure 282: Functional module diagram. I_1H and I_2H represent fundamental
and second harmonic values of phase currents.
I_2H/I_1H
This module calculates the ratio of the second harmonic (I_2H) and fundamental
frequency (I_1H) phase currents. The calculated value is compared to the set Start
value. If the calculated value exceeds the set Start value, the module output is
activated.
Level detector
The output of the phase specific level detector is activated when the fundamental
frequency current I_1H exceeds five percent of the nominal current.
Timer
Once activated, the timer runs until the set Operate delay time value. The time
characteristic is according to DT. When the operation timer has reached the
Operate delay time value, the BLK2H output is activated. After the timer has
elapsed and the inrush situation still exists, the BLK2H signal remains active until
the I_2H/I_1H ratio drops below the value set for the ratio in all phases, that is,
until the inrush situation is over. If the drop-off situation occurs within the operate
time up counting, the reset timer is activated. If the drop-off time exceeds Reset
delay time, the operate timer is reset.
The BLOCK input can be controlled with a binary input, a horizontal
communication input or an internal signal of the relay program. The activation of
the BLOCK input prevents the BLK2H output from being activated.
1YHT530004D05 D
615 series
Technical Manual